I have been seeing many people repeat this summary because it makes antisemitism look even more unique than it already is. Usually Herzlians are the ones parroting this phrase, but I am sure that there remain a few other people saying it in good faith, so I want to kindly explain why this summary is inaccurate.
Anti-Judaism (or ‘antisemitism’, if you find the distinction irrelevant) is indeed an ancient phenomenon. The Book of Esther, probably composed in or around 475 B.C.E., features a character called Haman, who unsuccessfully plotted a massacre against Jews. Although this was probably fictional, it remains clear that already in the fifth century B.C.E. some Jews were aware of a phenomenon that we now call anti-Judaism or antisemitism. Wikipedia suggests that it is even older: going back to 586 B.C.E., when the Neo-Babylonian Empire expelled thousands of Judean families to Babylon, and 740 B.C.E., when Assyria resettled thousands of Israelite captives. (I think that calling these last two instances ‘anti-Jewish’ is subjective, but we can worry about that elsewhen.)
That said, other categories of humans have suffered oppression long before the eighth century B.C.E. So if antisemitism is not the world’s oldest hatred, what is? I think that the answer should be obvious: misogyny. One example from Maura A. Matarese’s Finding Hope in the Crisis:
Merlin Stone […] offers evidence that the roots of misogyny began during the Bronze Age (3300–1200 BC), with the rise of the Indo Aryan civilization, whose intent was to conquer other societies and subjugate them. With this, the subjugation of women and the divine feminine began as well. Polytheism still reigned, but male gods had taken a higher position above female goddesses.xxxvii
Tony Greenstein, Norman Finkelstein, and no doubt many other Jewish adults will tell us that antisemitism is simply not the overwhelming terror that it once was. This need not mean that we should now consider antisemitism ‘unimportant’, only that we should think about it in a new way. Nevertheless, thinking of it as ‘the world’s oldest hatred’ is not the way to do it, because it is both unnecessary and ahistorical.